Rock sawing



C. MAKINSON Oct. 8, 1957 nited States Patent ROCK SAWING Clifford Makinson, Rosemere, Quebec, Canada, assignor to Terry Machinery Company Limited, St. Lauret, Quebec, Canada, a corporation of Canada Application April 14, 1955, Serial No. 501,378

Claims priority, application Canada February 15, 1955 4 Claims. (Cl. 125-16) This invention relates to a cutting apparatus of the type employing abrasive material rubbed by a moving blade against the surface of the work.

This type of device requires a continuous supply of nely divided abrasive material in the cutting zone. The usual manner of recycling this material to the cutting zone is by pumping it from a collecting basin beneath the cutting zone. See for example, U. S. Patents 2,537,445 (1951) and 461,221 (1891). The disadvantage of this method is that the abrasive material quickly wears out the parts of the pump. This results in costly replacements and repairs and shut-downs while they are being made. A suggestion is made in U. S. Patent 414,529 (1889) of using a suction jet apparatus to suck the abrasive from the collecting zone. This has the disadvantage that the jet is enclosed and remote from the source of the abrasive. In addition, the direct perpendicular impingement of abrasives from the jet on the wall of the conduit would quickly wear out the wall.

Appll'ccmrs development In accordance with the applicants development, the cutting apparatus is combined with special recycling means for the abrasive material and which overcomes ythe shortcomings of prior devices.

An apparatus according to the invention, involves means for supporting the stone in position to be cut. Cutting means including a blade adapted to rub the abrasive material against the work to produce the cutting attrition` is operable in the cutting zone. A reservoir of nely divided abrasive is arranged above the cutting zone. A collecting basin for collecting abrasive is arranged below the cutting zone. Special means is provided in accordance with the invention for conveying the abrasive from the collecting basin back to the reservoir. This conveying means includes a conduit lined with abrasive resistant material, for example, rubber, or synthetic rubber, leading from the collecting basin to the reservoir. This conduit has a mouth opening into the collecting basin at a level below the designated level for abrasive. A nozzle is provided, spaced from but directed at the mouth of the conduit. Pumping means is provided for supplying water under pressure to the nozzle. The conduit is preferably provided with a venturi throat spaced from the inlet.

The collecting basin for the abrasive is designed for the gravitation of the abrasive to the bottom of the basin, preferably with at least one sloping side and a receiving trough-like bottom portion. The abrasive gravitates and is guided by the sloping side wall into the trough portion so that a supply of abrasive always intervenes the jet and the conduit mouth and is blasted by the jet into the mouth and through the conduit.

Normally, there will be a head of a few inches of abrasive material, generally shot, in the collecting basin above the-inlet and jet. There is then a head ofwater 2,808,821 Patented Oct. 8,

above that which is governediby an outlet in the Vcollect- -ing basin or hopper. The head of abrasive is governed by the feed rate and by adding additional abrasive when necessary.

At the start of the operation, the operator fills the hopper with a quantity, for example, two or three hundred pounds of shot which will bring its level up to possibly two feet from the bottom of the hopper. At this point, there need be no water in thehopper. When the device is started, Water and shot is forced up through the conduit to the feeding reservoir above the sawing zone. The abrasive in the hopper then finds a.1evel several inches above the inlet. This will be governed by the speed of recycling and addition of the abrasive if necessary.

Where the device is idle for a period, a head of abrasive material may build up in the collecting hopper, for example, to about two feet. This is a fairly heavy mass. But, with the present system the starting up is no problem and the jet breaks the mass up quickly and the system can be put into operation without any special steps and without delay.

The invention will now be described by detailed reference to the drawings. By way of example, a granite cutting or grinding operation will be disclosed. The apparatus shown is a preferred one suitable for carrying out the invention and the process described is also preferred.

ln the drawings:

Figure 1 is a side elevation partly in section of a granite sawing apparatus.

Figure 2 is an enlarged fragmentary cross-sectional view partly in elevation showing the arrangement of the jet and intake in relationship to the collecting hopper and to the grinding material and water.

A indicates a frame for mounting the cutting apparatus.

A block of granite B is held on a mobileplatform-'C- mounted on wheels 15 running on rails 17 carried by the foundation D.

The frame A is made up of spaced apart guide posts 19 one at each side of the platform C. Cross beams 21 extend between the guide posts well above the cutting zone.

Spaced apart screw-threaded feeding shafts 23 are provided, one adjacent each of the guide posts. The screwed shafts 23 extend from lower foundations 25 to upper blocks 27 mounted on the top of the guide posts 19. Each of the shafts 23 passes through a runner 33 having a screw threaded part 34 having threads which engage those of the shafts 23. n

The runners 33 are provided with horizontal guide ways 35 which guide reciprocable shafts 37 on each of which is mounted a cutting blade 39. The shafts 37 are linked through a link or pitman 39 pivoted to it as at 41 to an eccentrically positioned driving pin 43 connected to the motor 45. The motor 45 is carried on a foundation block 47.

Above the cutting zone and mounted on the beams 21 is an abrasive reservoir 51. The reservoir 51 is provided with a Y branch having outlets 53 above the cutting zone to project abrasive on the cutting zone.

Beneath the cutting zone the oor'l of the base is formed to deliver abrasive to a hopper 61 which is provided with at least one sloping wall 61A and a receiving troughlike portion 63 in the bottom. Extending from the collecting hopper to `the feeding reservoir is a conduit 65. This conduit has an inlet end or mouth 67 which is positioned within the trough 63. Spaced from the inlet 67 the conduit has a narrowed portion 6 9 forming a venturi throat adapted to accelerate the ow of material through the conduit 65 from the inlet 67. The conduit has 3 aeresilient lining, for example, of rubber or synthetic rubber.

Within the hopper and directed at the conduit inlet 67 but spaced from it is a high pressure jet nozzle 71. The jet'no'zzle 71 isV fed by a conduit` 73 which receives water from. a pump 7S. VA conduit 77 leads from the source' of water to the pump. Y

There is also a pipe 76 leading from the pump to carry water to flush the floor 16. This pipe is controlled by a valve 78. The pipe 73- is controlled by a valve 74 so thatr the line 73 can be cut off if the operator wishes to flush the system only-and-not to recycle abrasive. 62 is anoutlet leading to-the drain. This serves to maintain the waterv level in the hopper. Dust and fine particles tend to be carried away through this pipe 62. The small particles areno -good for grinding.

Operation The cutting apparatus proper operates conventionally. The blade 39 is reciprocated back and forth by the motor 35. The blade 39 working through the medium of the abrasive finely divided material coming from the reservoir grindsy the rock away by attrition. The blade thus gradually works its way through the rock.

The finely divided material leaving the cutting zone is washed down the fioor 16 into the hopper 61 and collects in the trough 63.

The finely divided material is recycled to the cutting zone in a novel manner in accordance with the invention. This is accomplished by the high pressure jet of water coming from the nozzle 71 which forces the finely divided material from the trough 63 into the inlet 67 andthrough the conduit 65.

The material gravitates into the trough 63 down the sloping wall 61a and feeds forward into the conduit feeding zone and is progressively forced by the direct action upon it of the jet into the inlet 67 and through the pipe 65.

The resilient lining of the pipe 65 reduces wear to a The venturi throat`69 prevents back-flow and provides for even feed forward of the material. The finely divided material does not come into contact with any working parts and therefore does not wear out the pump.

The jet acts directly on the abrasive mass in the troughlike portion 63 of the hopper 61, and forces it into the inlet 67 and axially into the conduit 65. The naked jet is operative on the mass of abrasive gravitating continually into the bottom of the trough 63 under the pressurerof the mass above it.

The original starting up of the device is as follows. The operator puts two lOO pound bags of ball shot in the hopper. Then he starts up the pump. There is no water. in the device at that point. The shot is up to the level that is shown in the drawings. The pumpV starts, and through the jet action described to force water up the conduit with a certain amount of shot. There is excess water with this shot and thisgoes through the reservoir to wash the abrasive down the floor 16. There is always excess water and always an overflow in the abrasive hopper.

in a normal operation with a collecting basin or hopper about 3 feet deep, substantially the following conditions will prevail. At the start, the hopper will be full up to about 2 feetY from the bottom. When the device is running all the time, there will be a head of only a few inches of the abrasive, say, 4 to-6 inches above the nozzle.

would have to break up the mass with a crowbar, otherwise you wouldY not get itinto the pump. The watercarries away the dust that is too fine for ygrinding purposes-it is carried off in the water going down through the overflow pipe 62.

Pressures of from 50 to 500 pounds per square inch at the jet have been found' effective. A preferred pressure is about poundsper square inch.

The following are characteristics of the particular ap,- paratus and-process illustrated by wayof example.L

The abrasive material issteel or iron shot from lfs, of an inch to oflan inch in diameter which becomes mixed with granite` dust or particles from the sawing operation.v A typical size for Ythe pipe at the top of the machine, that is,"the delivery pipe for'the abrasive, is l'l/z inches inside diameter.V The jet nozzle is 1/2 inch inside diameter. The recycling conduit is ll/z inches in diameter with the venturi about 3;/4 of an inch. These of course are typical dirnensionsand can be varied within the scope of the invention. The venturi reduces turbulence in the conduit. There is expansion ofl the stream on the inside side of the venturi and this givesa low pressure areawhich forms a type of lock preventing back ow.

It should also beA explained that the pump must be of a capacity tosupply morewater than the jet can handle. This yexcess water is actually jet propelled into the. conduit 65'. For example, wherethel jet is taking 74 to 7S gallons per minute in aparticular installation, 12,4 to gallons per minute` will actually be passing through the conduit 65 where the head between the venturi and the receiver vessel,y 51 is about 22H feet. The material going through the conduit 65 kwill of course be a mixture of water andabrasive material. The pump will thusV have to have a capacity of 200 gallons perminute or more. In this particular case,Y the. pressure was 10() pounds per squareinch. Thesefactors will of coursedepend on the head Abetween the venturi 6 9 and the vessel 51.

I claim:

l. A rock cutting apparatuscomprising in combination a support for rock to be cut, a movable cutting element adapted by working `with abrasive to cut the rock by attrition, a reservoir for finely divided material used in the cutting operation and au outlet from said reservoir positioned to deposit said finely divided material in the cutting Zone, arhopper beneath'the cutting zone adapted to receive finely divided materialleaving the cutting zone, means forv channelling tothe hopper the finely divided materialleaving the cutting zone, a conduit leading from the hopper at a level below the depositing level of the finely divided material tosaid hopper, said conduit having an open end within` saidrhopper constituting a material receiving mouth, a portion of reduced diameter in said conduit spaced inwardly of said conduit open end and forming with theV unreduced'portions of said conduit a venturi'throat adapted to accelerate the flow of material delivered therethrough, ay high pressure nozzle mounted within said hopper and having a jetopening axially aligned with and directedvtowardsrsaid conduit open end in spaced relationship therewith, av pump connected to said high pressure nozzle whereby a high pressure jet may be set up to direct the finely divided material collected in said hopper` into and through said conduit open end and by said jet andconduitformati'on caused to flow through said conduit to said reservoir.

2. A rock cutting apparatus, as claimed in claim 1, wherein theportions of said conduit at each side of said portion of reduced diameterv are of equal diameter.

3. A rock cutting apparatus, as claimed in claim l. wherein the interior of said conduit is lined with resilient material,

4. A rock cutting apparatus, as claimed in claim l, wherein said hopper is providedwith at least onersloping side adapted todirect said finely divided material to the bottom ofk said hopper,jthe axis of said open end and` 5 pressure nozzle being perpendicular to said hopper sloping 326,323 side and located adjacent the lower end thereof. 1,921,697 1,925 ,75 1 References Cited in the le of this patent UNITED STATES PATENTS 507 816 315,171 Saunders Apr. 7, 1885 6 Patch Sept. 15, 1885 Owens Aug. 8, 1933 Diienderfer Sept. 5, 1933 FOREIGN PATENTS Belgium a- June 13, 1952 

